1. Field of the Invention
The present invention relates to an image forming apparatus, such as a laser printer, for receiving image data from, e.g., an external apparatus, and printing a recording image on a paper sheet on the basis of received data.
2. Description of the Related Art
Image formation in an image forming apparatus such as a laser printer is attained via, e.g., electrification, exposure, developing, copy, peeling, cleaning, and fixing processes. In such an image forming apparatus, an electrification unit, an exposure unit, a developing unit, a copy unit, a peeling unit, a cleaning unit, and the like are sequentially arranged around a photosensitive drum, and the apparatus also comprises a fixing unit for receiving a paper sheet from the peeling unit. These units are driven upon rotation of the photosensitive drum, thereby executing the above-mentioned image formation processes. In this manner, an image can be formed on a paper sheet.
In a laser printer of this type, a control system is divided into an engine control section for controlling the above-mentioned units to control operations for attaining the image formation processes and a printer control section for controlling operations of the engine control section. The engine and printer control sections are connected by exchanging commands and status data. The printer control section expands image information in units of pages supplied from an external equipment onto a partial memory to generate bit-image data, and then outputs the bit-image data to the engine control section.
In the laser printer, when the printer control section detects, based on the fact that a time required for expanding and generating the bit-image data on the partial memory exceeds a predetermined allowable time, that a defective image is formed, an alarm message for a user is transmitted outside a printer using a display unit incorporated in the printer.
When a continuous print operation including various print contents in units of print pages is performed, the following problem arises. More specifically, even when a time required for expanding and generating bit-image data of a print content of a given page on the partial memory exceeds the allowable time, and a defective image is formed, an alarm message transmitted outside the printer merely indicates that a defective image is formed on a certain page or pages during the continuous print operation, and a page/pages on which a defective image is formed cannot be specified.